In a medium bowl, whisk together pancake mix, milk, eggs, oil and cinnamon until smooth. If the batter seems too thick, add a little more milk to thin it out.
Fold in shredded apple then pour batter on hot griddle, 1/2 cup at a time. Cook until pancakes are golden brown, about 2-3 minutes on the first side and 1-2 minutes on the second side. Serve with maple syrup and thinly slices apples if you wish.